i've been thinking of going unholy for tanking, regardless of the correct spec atm, i'm just after some clear tanking rotations, so far what i've puzzled out is
IT ---PS---pestilence---DnD---Blight--- then alternatively bloodboil and Scourge strike/obliterate (i guess this depends on whether you have annihilation or not and mob armor).
Another thing would be our CDs, in a rough patch, i'd pop bone armor, then icebound fortitude and then lichborn, but it seems that i end up runninb out of CDs to protect myself and then get smashed, any ideas on how to improve this?